Reactions of the halogens

4 marks · Normal

This question is about the reactivity and displacement reactions of the halogens.

(a)

Write a balanced equation for the reaction of chlorine with potassium bromide solution.

[1 mark]

(b)

Explain why this reaction happens.

[2 marks]

(c)

Name the type of reaction taking place in part (a).

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) Cl2(aq) + 2KBr(aq) → 2KCl(aq) + Br2(aq)

(b) Chlorine is more reactive than bromine, so chlorine displaces bromine from potassium bromide.

Common mistakes: reversing reactants/products; wrong explanation of reactivity series

Show mark scheme and worked solution

Marking points

A1 (a) · 1 mark · Correct balanced equation: Cl2 + 2KBr → 2KCl + Br2; state symbols not required.

M1 (b) · 1 mark · States that chlorine is more reactive than bromine.

M2 (b) · 1 mark · Chlorine displaces bromine from bromide compound (displacement explained).

B1 (c) · 1 mark · Names the reaction as 'displacement reaction'.

Worked solution

a) Cl2(aq) + 2KBr(aq) → 2KCl(aq) + Br2(aq)

b) Chlorine is more reactive than bromine, so chlorine takes the place of bromine in the compound, forming potassium chloride and releasing bromine.

c) Displacement reaction